Fluid control system



Sept. 26, 1939. w. v. SAUTER Er AL 2,173,886

FLUID CONTROL SYSTEM y Filed Jan. 14, 195s sheets-sheet 1 Sept. 26, 1939. w. v. SAUTER ET AL FLUID CONTROL SYSTEM l 4 sheets-sheet 2 Filed Jan. 14, 1936 Y v i ml M as, u

Sept. 26, 1939. w. v. SAUTER ET Al.

FLUID coNTRL SYSTEM Filed Jan. l14, 1936 44 sheets-sheet 3 Sept. 26, 1939. w. v. SAUTER Er AL. 2,17386 FLUID CONTROL SYSTEM Filed Jan. 14, 1936 4 Sheets-Sheet 4 r 8 1 nr l :an a f. www f WQ 1mm., .W Qu A r 6W r. li i, M7 -w e NQ y, W7 q Hl y A'Hk Patented Sept. 26, 1939 UNITED STATES PATENT OFFICE FLUID CONTRL SYSTEM Application January 14, 1936, Serial No. 59,043

13 Claims.

This invention relates to fluid control systems, and more particularly to systems employed to control the ow of draft air to stoker furnaces.

In Stoker furnaces it is well known that for variable fuel burning rates, variable quantities of draft air must be supplied to effect efficient combustion of the fuel. For each change in fuel burning rate, as determined by the boiler requirements, a corresponding change in pressure of the air supplied to the fuel bed also takes place. 'I'he devices employed to control the flow of draft air to the fuel bed must thereforeV be capable of operating eectively throughout the range of operation of the furnace.

One object of the present invention is to provide a control system for furnace draft air which functions automatically to insure the proper flow of air to the fuel bed under all conditions of operation.

m Another object is to provide a control damper for each furnace tuyre or group of tuyres which responds to the changes in the density of the fuel bed overlying the same, and to provide control means for such dampers which respond to the 25 changes in pressure at the source of air supply to maintain the dampers in balance throughout the range of operation of the furnace.

A more specific object is to provide a damper for each tuyre or group of tuyres which is operated by the differential pressure created by the flow of air therethrough, and to provide an additional control therefor which is acted upon by the pressure in the plenum chamber so that the dampers will function at all -times to permit the 35 proper amount of air to flow therethrough to the fuel bed.

Other and further objects will become apparent as the description of the invention progresses.

Of the drawings:

Fig. l is a longitudinal view partly in section taken through one of the tuyre chambers of a Stoker, showing one form of air control mechanism, comprising the present invention.

Fig. 2 is an enlarged view partly in section 'taken through one of the tuyre chambers of the Stoker showing the preferred air control system associated therewith.

Fig. 3 is an end view taken substantially along line 3-3 of Fig. 2.

Fig. 4 is a View partly in section of a valve forming a part of the control system shown in Figs. l and 2.

Fig. 5 is an enlarged view partly in section showing a modified form of control mechanism.

Fig. 6 is a view partly in section showing a further modif-led type of air control system.

Fig. 7 is a similar view disclosing a still further modification of the type of air control shown in Figs. 1 to 5.

Fig. 8 is a side elevational View partly in section of a stoker showing another embodiment of the present invention.

Fig. 9 is a side elevational View partly in section of the upper portion of a Stoker showing a still further embodiment of the present invention.

The present invention, for the purpose of illustration, is shown applied to a Stoker of the underfeed type wherein the tuyres and communieating passages thereto constitute the ducts Which receive air from a common plenum chamber. The communicating passages to these tuyres are bounded on one side by movable dampers, while the other sides thereof are fixed. The static pressures operating against the inner sides of these dampers are substantially the same as that of the air flowing through the associated tuyres providing, of course, that the areas of the passages and the associated tuyre openings are substantially the same. For a given rating the pressure of the fluid in the plenum chamber remains substantially constant, and since but little movement of the air occurs in this chamber, the total pressure therein is substantially static pressure. 'I'he dampers may be so disposed that the outer sides thereof are subjected to the pressure of the fluid in the plenum chamber, or they may overlap so that a portion of the outer side of each forms a part or the whole of the upper wall of an adjacent communicating passage, and therefore is controlled, to a certain degree, by the static pressure of the air in said adjacent passage.

As is well known in the art, the combustion chamber disposed above the tuyres is maintained at a pressure materially lower than that of the plenum chamber, and` accordingly the air flows through the tuyres in the direction of the combustion chamber. The rate of flow through the tuyres is determined largely by the resistance offered thereto created by the density of the fuel bed supported by the tuyres. As the fuel bed decreases in density it is apparenty that the rate of flow through the tuyres increases, and vice versa as the density of the fuel increases the rate Vof flow through the tuyres decreases.

Therefore, since one side of each damper is subjected substantially to the static pressure of the air flowing through the tuyres, Vwhile the other side thereof may be subjected wholly, or .in part, to the total pressure of the air,'it is seen that when any flow exists past the dampers they are subjected to differential pressures. In actual practice the weights of the dampers are so proportioned as to counteract a predetermined differential pressure. `In other words, the weight of each damper is so proportioned that it will remain open until the fuel bed overlying the associated tuyre becomes abnormally thin, at which time the differential pressure acting therein has increased to suoli an extent as to overcome this dead weight and as a result the damper will move to closed position, thereby shutting off the flow of air to the associated tuyre.

Now, in the event it is necessary to operate the furnace at a higher rating, which obviously requires a greater quantity of air to flow through the tuyres, the pressure of the air in the plenum chamber must necessarily be increased. Under these conditions it is seen that if the density of the fuel bed is substantially the same as it was while operating at the lower rating, thenthis increased pressure in the plenum chamber will cause an increase in the flow of air through the tuyres, subjecting the dampers to a greater differential pressure, and thus creating an unbalanced condition.

The present invention contemplates the provision of automatically operable compensating means for each of the dampers which retains the latter in balanced condition for each change in furnace rating so that the dampers will only close when the fuel bed over the associated tuyres becomes abnormally thin.

'Ihe accompanying drawings show several types of compensating devices for the dampers which may be utilized to maintain the same in balanced condition throughout the range of operation of the furnace, and each type will now be described in detail.

Referring to the drawings, numeral I designates a stoker of the underfeed type having alternately disposed retorts 2 and tuyre rows 3. Fuel is supplied to the retorts 2 from a hopper 4 and any suitable feeding device .driven by a power mechanism indicated at 5, feeds the fuel gravitating in hopper 4 to the retorts 2. A series of pushers 6 mounted in the bottom of each retort 2 is also operated by the power mechanism 5 through the operating connections l. These pushers underfeed the fuel along the retorts and tuyres to an extension grate 8, which in turn overfeeds the fuel to an ash pocket or dump plates (not shown) disposed at the rear of the stoker, in a well known manner.

It is to be understood that the invention herein described is not to be limited to its application to underfeed stokers, since it is equally adaptable for use in connection with other types of stokers, as well as other apparatus wherein fluid control is desired. Y

When the terms front and "rear are hereinafter used in connection with the description of the elements of the Stoker I and the associated fluid control, it will be understood that the portions of such parts extending toward the rear or extension grates 8 will be .designated as rear, and those portions thereof extending toward the front or driving mechanismy 5, of the stoker will be designated as front. Y

Referring more particularly to Figs. 1 to 3 `inclusive, which illustrate the preferred embodiment of the present invention, each tuyre row 3 comprises a series of superimposed tuyreA blocks I0, each having rounded rear portion II, and a substantially rectangular front portion I2 termnating in a flat tailpiece I3. Tuyres I may be of the general type shown and described in United States Patent No. 1,930,908, and rest upon the side plates I4 forming the side walls of the retorts and tuyre chambers respectively of the stoker. As shown more particularly in Fig. 2, the tuyre blocks I0 in assembly are so constructed as to form a series of passages I5 therebetween through which the draft air from the plenum chamber I6 .disposed beneath the stoker, flows to the fuel bed supported thereby.

The control system illustrated in Figs. l to 3 of the drawings consists of a series of damper elements I8 pivotally mounted on pins I9, supported in the side walls 20 of a frame 2I. Each of thc frames 2l in the present instance supports eight dampers, although they may be constructed so as to support any desired number without 4departing from the invention Each frame 2| comprises a series of cross members 22 connecting the side walls 20 thereof, and each frame is secured to the interior of the retort side walls I4 by any suitable securing means, such as by bolts 23. Each unit is placed beneath the tuyre blocks lll in such a manner that the beveled forward portions 24 of the tailpieces I3 thereof lie in substantially abutting relation with the upper surfaces of cross members 22, as shown in Fig. 2.

Each damper I8 consists of a substantially flat portion 25 extending between the side walls 20 of frame 2 I, and a vertically disposed substantially arcuate portion 2G, which in assembly lies in substantially abutting relation with the vertically disposed substantially arcuate forward surface 2! of an associated cross member 22. Suflcient clearance is provided between portion 26 of each damper and the corresponding arcuate surfaces 21 of cross members 22 to permit free movement of the dampers. The lower surfaces 28 of the cross members 22 are inclined and lie in substantially parallel relation with flat portions 25 of the dampers i8 and form therewith passages 2S communicating with the inlet passages I5 of the associated tuyres. The arcuate surfaces 21 of cross members 22 each terminate rearwardly of the forward edges thereof forming ledges 3l] upon which the lower end of the arcuate portions of the dampers rest when the latter are in fully open position, as shown in Fig. 2. By this construction itis seen that the upper surface of each damper is subjected to the static pressure of the air flowing through its associated tuyre, while the lower surface thereof is at all times subjected to plenum chamber pressure. Therefore, when any flow exists in the passages 29 and I5 the associated dampers will be subjected to a differential pressure.

For a fuel bed of uniform density throughout, it is believed to be apparent that this differential pressure will Vary for each change in plenum chamber pressure. At relatively low fuel burning rates when the pressure in the plenum charnber is maintained at an intensity equal, for example, to 2 inches of water, the differential pres- -dampers in accordance with the changes in fuel fao burning rates, a compensating device'32 has been provided for each damper.

Each compensating device comprises a cylinder 33 having a piston 34 operating therein. The upper end of each piston 34 is operatively connected to an associated damper I8 by any suitable connection 35. Each cylinder 33 is connected to a pipe or duct 36 extending longitudinally of the tuyre chamber, which is closed at the lower end 31 thereof. The upper end of pipe 36 extends through the front wall of the Stoker, and is connected to a pipe 36' extending transversely of the Stoker, and to which the pipes 36 for the other tuyre chambers are also connected. A pipe 36" is connected at one end to pipe 36', and at the other end to a chamber 38 subjected to an auxiliary source of pressure by means of any suitable fan mechanism 39. Pipe 36" has mounted therein a three-way valve 40, provided with ports 43, 44 and 45, and a gate valve 4l. As shown more particularly in Fig. 4, Valve 46. may be actuated manually to different positions of adjustment by means of a handle 42. When handle 42 is in the full line position shown in Fig. 4, pipe 35 is con-- nected to atmosphere through ports 43 and 44, and when said handle is moved to the dotted line position ports 44 and 45 will be in vertical alignment thereby establishing communication between chamber 38 and pipe 36" While port 43 communicates with a relief valve 4S. Relief valve 49 comprises an inlet port 49 and a discharge port 49". A valve element 48"' held in closed position b-y a spring 49 normally prevents the escape of fluid through said valve. The pressure of spring 49iv may be varied by an adjustable plug 49V. By means of gate valve 4| the amount of fluid supplied to pipes 36 from chamber 38 may be varied. It therefore is seen that when valve 46 is adjusted to the position shown in Fig. 4, pipe 36, and consequently pipes 36 and 36, will be connected to atmosphere, and thus the lower end 46 of each piston 34 is subjected to atmospheric pressure, while the upper surface 41 thereof is subjected to plenum chamber pressure.

When valve 46 is in this position the force tending to hold each damper in open position not only consists of its own weight and the weight of the associated piston 34, but also of the additional force created by the plenum chamber pressure acting on the upper surface 41 of said piston. The force exerted upon the upper surface 41 of each piston obviously varies with the changes in plenum chamber pressure. Therefore, when the plenum chamber pressure reaches a maximum intensity the greatest force tending to hold the damper open will be exerted upon each of the dampers, and vice versa when the plenum chamber is of minimum intensity a minimum force will be imposed upon said dampers. The size and weightl of each of the pistons 34 are so proportioned as to enable the associated damper to close when a predetermined differential pressure is imposed thereon. This predetermined differential pressure is determined by the resistance offered to the free flow of air through the associated tuyres for a fuel bed of a given density. For example, when the density of the fuel bed is reduced so that a bare spot would soon occur therein the differential in pressure acting upon the corresponding damper or dampers will be suiciently great to cause the same to move upwardly to closed position, as indicated at 58 in Fig. 2. After the fuel feeding elements have built up that portion of the fuel bed to a greater density, the dampers will move downwardly to open position,

permitting air to again ow therethrough to the fuel bed.

Now let us assume that a greater fuel burning rate is required, and as a consequence thereof the plenum chamber pressure is correspondingly increased so as to cause a greater flow of air through each of the dampers. When this change occurs each damper will be acted upon by a greater difference in pressure but this will be counteracted by the action of the plenum chamber pressure upon the upper surface 41 of piston 34, and as a result the damper will remain open so long as the fuel bed remains normally uniform. However, should thin spots develop in the fuel bed over any of the tuyres the corresponding dampers will consequently be subjected to a still greater difference in pressure caused by the more rapid flow of air therethrough, and as a result the dampers will move to closed position to again shut off the air to those portions of the fuel bed.

It therefore is seen that the compensating devices 32 function to establish a balanced condition for the dampers due to each change in rating, and as a result the dampers Will close only when thin spots occur over the associated tuyres.

It sometimes is desirable to subject the lower end 46 of each piston 34 to a pressure either above or below atmospheric pressure to eifect balancing of the dampers. To this end the valves 40 and 4| are provided. When it is desired to operate the system in this manner lever 42 is swung to the dotted line position shown in' Fig. 4., and gate valve 4i is so manipulated as to impose the desired pressure in pipes 36, and consequently in each of the cylinders 33. In order to determine the pressure to which the lower ends of pistons 34 are subjected, a manometer 5l is provided in pipe 36 adjacent control valves 40 and 4I. Thus, by simply manipulating gate valve 4I the desired pressure may be imposed upon the lower ends of pistons 34. The tension of spring 49iv acting on relief valve 49 is then adjusted by manipulation of plug 49v so that said valve will open when the pressure in pipe 36 exceeds this predetermined pressure. When suflicient pressure has been introduced in pipe 36, gate valve 4I is fully closed. If the pressure in pipe 36 is less than that in plenum chamber I6, any leakage past the pistons 34 will tend to increase the pressure in said pipe. However, when this occurs relief valve 49 will open to exhaust to relieve pipe 36 of this additional pressure. When this pressure becomes normal again spring 49iv will close the Valve. In cases where the dampers I8 are unusually heavy it may be necessary to impose a pressure at the lower ends of pistons 34 greater than that in the plenum chamber. Under these conditions a nonexible link connection is provided between the dam-pers and their associated pistons 34. When it is desired to impose a pressure at the lower ends of pistons 34 less than that of atmospheric pressure, fan 38 is so operated as to produce a partial vacuum in chamber 38, and consequently in pipes 36, 36', 36 and cylinders 33.

It sometimes is desirable to have the dampers associated with each of the tuyres, overlay so that the conditions of the fuel bed which determine the iiow through the various tuyres will control to a certain extent the operation of the adjacent dampers. To this end the construction shown in Fig. 5 has been provided. In this construction each damper is provided with relatively flat upper and lower surfaces 56 and 51 respectively, which terminate at the rear ends thereof in a substantially arcuate portion 58. A

frame 59'in which 'these dampers are mounted is valso provided with cross members 6l) against which the forward ends of the tuyre blocks abut. The forward surface 6| of each cross member 68 is also of substantially arcuate construction corresponding to the curvature of portions 58 of the dampers 55. Each damper 55 has associated therewith a compensating device 32 similar in construction and operation to those shown in Figs. 1 to 3 of the drawings. In this construction, owing to the overlapping of the dampers, the pressure conditions of the air flowing past any of the dampers controls, to a certain degree the operation of the next adjacent dampers of the series. Due to this counteracting relationship between the adjacent dampers, each will remain at least partially open unless a comparatively great area of the fuel bed becomes abnormally thin. In other words, the lower surface of each damper isnot entirely subjected to plenum chamber pressure, but rather, to a certain extent, to the pressure of the air flowing past the next lower damper so that the differential pressure to which it is subjected is somewhat reduced.

In the construction shown in Fig. 5 a somewhat different means is provided for introducing pressure to the lower ends of the pistons 34 operating in the cylinders 33 of the compensating devices 32. As shown in Fig. 5, the pipe 35a to which the cylinders 33 are connected, has provided therein a series of small apertures 62 through which fluid pressure from the plenum chamber I6 enters. 'I'he outer end of pipe 36a may be connected to a pipe 36b extending across the front of the stoker. A pipe 36C depends from pipe 36b and has provided therein a relief valve 63. A spring 64 normally retains the valve element 64 of said valve in seated position, and the pressure of said spring is adjusted by means of a plug 64 making threaded contact with the lower end of the valve casing. A manometer 5| is also attached to the outer end of pipe 36a adjacent valve 63, so that spring 64 may be so tensioned as to permit unseating of valve S3 when the predetermined pressure desired in pipe 86"L is exceeded. Plug 64" may also be so adjusted that the valve will remain open. The lower ends of pistons 34 will then be subjected to atmospheric pressure. 'I'he type of dampers shown more particularly in Fig. 2 may be substituted for that shown in Fig. 5 without departing from the invention. In certain installations it may be desirable to control the air to a group of adjacent tuyres rather than to the individual tuyres, and to this end the construction shown in Fig. 6 has been provided. For the purpose of illustration, the tuyres 65 shown therein have been arranged in groups of four. Extending forwardly of each group of tuyres are partitions 66 and 61 respectively, which form an inlet passage 68 to each of such groups of tuyres. Partition 66 is substantially flat and terminates at the front end thereof in an arcuate portion 59, while partition 61 is of arcuate construction. The lower end of partition 61 is connected to a substantially flat portion 19 which joins at the forward end thereof the lower end of arcuate portion 59. A damper 1| is pivotally supported between the tuyre supports 12 and comprises substantially flat upper and lower surfaces 13 and 14 respectively, which terminate at their rearwardly disposed ends in a substantially vertical arcuate portion 15. Arcuate portion 15 lies in substantially abutting relation with the forward surface of arcuate portion 69, and when actuated to closed position; as shown in dotted lines. in Fig. 6, en gages the lower forwardly disposed end of partition 61. To prevent movement of the dampers 1| out of operative position a series of stops 16 are provided. A compensating device 11 is also provided for each damper 1|. These compensating devices are similar in structure and operation to those shown in Fig. 2, and accordingly, a detailed description thereof is unnecessary. It therefore is seen, that when the differential in pressure acting on surfaces 13 and 14 of each damper is suflicient to overcome the dead weight thereof, and also the action of the piston provided in compensating devices 11, the damper will move to closed position. In this case also the operation of the dampers is effected only by changes in the density of the fuel bed overlying the associated groups of tuyres. The compensating devices in this construction also maintain the dampers in balanced condition for each change in' furnace operation.

Fig. 7 shows a construction on the order of that shown in Fig. 6, but having a somewhat different damp-er arrangement provided therein. In this construction the tuyres 88 are also arranged in groups of four, each group having partitions 8| extending downwardly therefrom between the tuyre supporting plates 84. A damper is pivoted at one end adjacent the lower end of partition 8|, and rests upon a stop 86 when in its fully open position. Partitions 8| each have a forwardly extending projecting portion 81 which lies in substantially parallel relation with the dampers 85 when the latter are in fully open position, and forms therewith a throat opening 88 communicating with the passage 89 defined by partitions 8|. In this construction a compensating device 90 is also provided for each damper 85. These compensating devices are similar in structure and operation to those shown in Figs. 1 and 2, and accordingly a detailed description thereof is unnecessary. The lower surface of each damper 85 is subjected to the pressure in the plenum chamber, while the upper surface thereof is subjected to the pressure of the air in passages 88 and 89, as determined by the fuel bed resistance over the associated group of tuyres. Therefore, when this differential pressure reaches a predetermined value caused by a diminishing in the fuel bed resistance, the damper will move upwardly toward closed position, as indicated by the dotted lines in Fig. 7, thereby shutting off the air supply to that portion of the fuel bed. When the fuel feeding elements build up that portion of the fuel bed, thereby creating a greater resistance to the flow of air, dampers` 85 will again move to open position by the action of compensating device 98 and the dead weight of the damper itself, as previously described.

Fig. 8 shows a still further modification of the present invention. In this construction, like the previously discussed constructions, the tuyres 9| also abut at the forward ends thereof the cross bars 92 of a framework 93. A damper 94 pivotally supported at the sides thereof in framework 93 is provided with an arcuate member 95 which lies in substantially abutting relation with the forward-vertically disposed substantially arcuate surface of an associated cross member 92. Each damper 94 is provided with a depending extension 96 terminating in an arcuate portion 91. Each arcuate portion 91 lies in operative relation with a nozzle 98 extending upwardly from a pipe 99. Pipe 99 is closed at the lower end thereof, while its forward end extends through the front wall of the stoker and is connected to a communicating pipe |00. Pipe extends across the front of the stoker, and has also connectedthereto the pipes 99 for. the other tuyre chambers of said stoker. A pipe |0| is connected to pipe |00 at one end thereof, the other end of which is connected to a const ant pressure chamber |02. Pressurey is supplied to pressure chamber |02 by any suitable fan |03 through a pipe |04. Mounted in a bracket secured to the :door of the'furnace room is a vertically disposed pressurev regulator |06 of the bellows type. Pressure regulator |06 comprises a casing |01 having a movable plate |08 provided therein. The left hand side of plate |08 is connected to the pressure in plenum chamber 09 by means of a pipe |0. Plate |08 has secured thereto a guide rod mounted for reciprocation in a bearing ||2 provided in cas- Guide rod is suitably connected to a valve rod ||3 .of an adjustable valve Y||4 provided in pipe |0| adjacent pressure regulator |05. A sliding valve element ||5 is secured to the rightJ hand end of valve rod ||3, and is adapted to be moved toward closed position by the operation of diaphragm |08.` Valve rod ||3 has provided intermediate the ends thereof a stud I6 which engages into an extended slot ||1 provided near the upper end of a lever ||8. Lever ||8 is pivoted intermediate its ends at ||9 to a laterally extending bracket |20fsecured to casing |01. A weight |2| is pivotally mounted at the lower end of lever ||8.

In this construction the nozzles 98 supplied with variable amounts ofr fluid from chamber V|02 through pipes mi and 99, constitute the compensating device for dampers 94. Fig. 8 shows the parts in normal position at which time valve ||4 is fully open, permitting a maximum amount of fluid to flow through pipes |0|, |99 and 99 and be discharged through nozzles 98. As pointed out in connection with the description of the other embodiments of the present invention, when the Stoker is operating at low ratings requiring a reduced plenum chamber pressure, the differential pressure acting on any of the dampers is relatively low. As the Vplenum chamber pressure increases, the diierential pressure acting on the dampers increases correspondingly providing, of course, in each case the fuel bed remains normally uniform. Accordingly, in order to enable the dampersto function properly for the different ratingsv a .compensating device must be provided. In thisinstance the dampers are so weighed that'assistance is required to cause them to close, even when the fuel bed resistance is materially reduced when the stoker is operating at the lower ratings. When the parts are in the position shown in Fig. 8, the iluid pressure from chamber |02 is unrestricted, and consequently a maximum amount of air is directed against the arcuate portions 91 of the dampers 94. The pressure so derived, however, is not suilicient to cause the dampers to close; it merely compensates for the change in dierential pressure due to operation of the furnace at a low'rating.. In the event the fuel bed should become abnormally thin over any of the tuyres, causing aV greater flo'w of air therethrough, the increase in differential pressure created thereby, coupled with the assistance from the jets of air pressure from the associated nozzles 98, will be suflicient to cause closing of the dampers.

ber |5| through'a pipe |52. lcured thereto a guide rod |53 slidably supported Now; as the fuel burning rate increases, causing an. increase in plenum chamber pressure, plate |08 will move to the right a corresponding amount, thereby causing valve ||5 to partially shut olf the supply of uid pressure to pipe |0|. When this occurs a reduced force will be imparted to'dampers 94 by the action of nozzles 99 to compensate for the difference in differential pressure to which the dampers are subjected by reason of this increase in plenum chamber pressure. When the stoker is operated at a maximum fuel burning capacity, plate 08 will have actuated valve ||5 to fully closed position, thereby completely shuting oil` the air to nozzles 98 from the source of supply |02, and the dampers 94 will then be acted upon only by the differential in'pressu're created by the ilow of air therethrough from plenum chamber |09. Plate |08 will be held in fully operated position against the action of weight |2|, so long as the pressure in chamber |09 remains at this maximum value. Weight |2| obviously exerts a progressively greaterY counteracting. force as lever ||8 approaches a horizontal'position due tothe progressively greater moments of said weight. When the pressure in the plenum chamber. decreases due to a lower fuel burning rate, weight |2| will actuate valve ||5 toward open position a corresponding amount, and consequently a corresponding amount of fluid will be ejected from nozzles 98 against the portions 91 of dampers 94'. This compensates for the reduction in the differential pressure acting upon the dampers caused by the reduction in plenum chamber pressure.

Fig. 9 shows a still further modification of the present invention. In thisV case also lthe tuyres |25 engage the cross members |26 of a frame |21 in which are mounted a series of dampers |28, one for each of the tuyres |25. Suspended from each damper |28 intermediate the ends thereof, is a weight |29. These weights are suspended byl wires, rods or anyother suitable means |30 which pass through eyelets |3| provided on a reciprocating rod |32. A downwardly extending arm |33 is secured to rod |32 which has provided at the lower end thereof a slot |34 which 'receives a pin |35 provided at the inner end of a second reciprocating rod |36. Rod |36 is guided for reciprocation in the front wall |31 of the stoker andin a guide bracket |38 extending downwardly from the front end |39 of the stoker. Ex-

tending forwardly frorn bracket |38 is a Scale |40. Rod |36 has secured thereto near the right hand end thereof a pointer |4| disposed in operative krelationjwith scale |40. Rod |36 has provided near the outer end thereof a block |42 ate its ends at |46 to a bracket |41 secured to and extending forwardly of a vertically disposed pressure regulator |48 an-d a weight |49 is pivotally mounted at the lower end of said lever. Pressure regulator |48 is of the bellows type having a movable plate |50 which is connected at the left hand side thereof to the plenum cham- Plate |50 has sein the casing of pressure regulator |48, and the outer'end of said rod is pivoted at |54 to lever |45. By this arrangement it is seen that when 'the pressure in plenumv chamber |5| increases, plate |50 will actuate the lever |45 in a coun- Aterclcckwise direction about itsr pivot, causing rods |36 and |32 to move to the left, and when the pressure reaches its maximum intensity lever |45 will have been moved to the dotted line position shown in Fig. 9. By this action each 0f the weights |29 will also be moved to the left, whereby the moments thereof are increased, and asa result the weights exert a greater downward force on the dampers |28. This increased force, tending to hold each damper open, compensates forthe increase in differential pressure acting on the dampers due to the increase in plenum chamber pressure, tending to move them toward closed position. As the pressure in the plenum chamber |5| decreases weight |49 will tend to move rods |36 and |32 to the right, thereby reducing the moments of weights |29, and consequently reducing the downward force imposed on the ,dampers |28 `to compensate for this reduction in differentialpressure. When the furnace is operatedat an extremely low rating the parts will assume the position shown in Fig. 1 wherein the weights |29 exert a reduced downward pressure on dampers |28. The dampers |28 thus remain balanced throughout the operating range of the furnace, and move to closed position only when the fuel bed overlying the associated tuyres becomes abnormally thin or porous.

In the event it is desired to adjust the weight |29 without the use of the pressure regulator |48, pin |43 is simply removed. Rod |36 may then be reciprocated manually from a knob |60 providedV at the extreme right hand end thereof. Scale |40 is provided to enable proper manual adjustment of the weights |29.

While the embodiments herein described are admirably adapted to fulll the objects primarily stated it is to be understood that the invention is not to be limited thereto since it may be embodied in other forms, all coming within the scope of the claims which follow.

What is Iclaimed is:

l. In ar -device of the class described, the combination of a tuyre block adapted to receive uid from a source of supply, means including a damper defining an air inlet Vpassage to said tuyre block, one side of said damper being subjected to the pressure of the fluid in said passage, and the other side thereof being subjected to the pressure at said source of supply, whereby when said differential pressure exceeds a predetermined value said damper moves to closed position, and means controlled by the fluid pressure at said source of supply for further controlling the operation of said damper.

2. In a device of the class described, the combination of a series of tuyre blocks having passages therebetween adapted to receive fluid from a source of supply, a damper for each ofsaid passages for controlling the flow of fluid therethrough, one side of each of said dampers being subjected to the pressure of the fluid in an associated passage and the other side thereof being subjected to the pressure at said source of supply, whereby when said differential pressure exceeds a predetermined value said damper moves to closed position, and a plurality of automatic means for controlling the operation of said dampers, one of said automatic means being provided for each of said dampers, each of said automatic means comprising a piston and a cylinder therefore, one end of said piston being subjected to the fluid pressure at said source of supply, and means for connecting the other end of said piston to another source of pressure.

3. In a device of the class described, the comemesse bination of aseries of tuyre blocks having passages therebetween adapted to receive uid from a source of supply, a damper for each of said passages for controlling the flow of uid therethrough, one sideof each of said dampers being subjected to the pressure of the fluid in an associated passage and the other side thereof being subjected to the pressure at said source of supply, whereby when said differential pressure exceeds a predetermined value said dampers move to closed position, a plurality of automatic means for controlling the operation of said dampers, one of said'automatic means being provided for each of Vsaid damperseach of said automatic means'comprising a piston and a cylinder therefon-one end of saidpiston being subjected to thefluid pressure at said source of supply, an auxiliary source of fluid pressure, means connecting the otherV end of said piston to said auxiliary source of, pressure and valve means for controlling the pressure delivered to said pistons from said auxiliary source of pressure.

4. In al device of the classdescribed, the combi-nationof a tuyre block adapted to receive fluid from a source of` supply, means defining an inlet passage to said tuyre block a damper mounted adjacent said passage for controlling the flow of fluid therein, one side of said damper being subjected to theV pressure of the fluid in said passage,and the other side thereof being subjected to the pressure at said source of supply, whereby when said differential pressure exceeds a predetermined value said damper moves to closed position, and automatic means controlled by the fluid pressure. at said source of supply'for further controlling theoperation of said damper.

5. In apdevice of the class described, the combination of a series of tuyre blocks, means forming passages between said tuyre blocks adapted to receive fluid from a source of supply, a damper for each of said passages for controlling the flow of fluid therethrough, one side of each of said dampers being subjected to the pressure in the associated passages, and the other side thereof partially overlapping the next lower damper of the series, thereby being subjected partially to the pressure `in the next lower passage and partially to theY pressure at said source ofsupply whereby, when said differential pressure/exceeds a predetermine'dvalue said dampers will move toward closed position, and a plurality of automatic means, one for each of said dampers, actuated by the pressure at said source of supply for further controlling the operation of said dampers.

'6. In a Vdevice, of the class described, the combination of a series of tuyre blocks having passages therebetween adapted to receive fluid from a source of supply, a damper for each of said passages for controlling the flow of fluid therethrough, one sideof each of said dampers being subjected to the pressure of the fluid in the associated passages, and the other side thereof being subjected to the fluid pressure at said source of supply, whereby when said differential pressure exceeds aV predetermined value said dampers move toward closedposition, and a plurality of automatic. means for further controlling the operation Vof said Vdampers in accordance with changes in pressureat said source of supplyone of said automatic means being operatively connected to each of .said dampers, each of said automatic vmeanscomprising a piston and a cylinder therejfor, one end of said piston Ybeing subjected to the rfluid pressure at said source of supply, means for connecting the other end of said pistons to pres- Sure delivered from said source of supply, and means for maintaining said last mentioned pressure at a predetermined value.

'7. In a device of the class described, the combination of a series of tuyre blocks having passages therebetween adapted to receive fluid from a source of supply, a damper foreach of said passages for controlling the flow of fluid therethrough, one side of each of said dampers being subjected to the pressure of the fluid in the associated passages, and the other side thereof being subjected to the iiuid pressure at said source of supply, whereby when said differential pressure exceeds a predetermined value said dampers move toward closed position, and a plurality of automatic means for further controlling the operation of said dampers in accordance with changes in pressure at said source of supply, one of said automatic means being operatively connected to each of said dampers, each of said automatic means comprising a piston and a cylinder therefor, one end of said piston being subjected to the iiiLd pressure at said source of supply, means for connecting the other end of said pistons to pressure delivered from said source of supply, and an adjustable relief valve for maintaining said last mentioned pressure at a predetermined value.

8. In a device of the class described, the combination of a series of tuyre blocks having passages therebetween adapted to receive uid from a source of supply, a damper for each of said passages for controlling the flow of fluid therethrough, one side of each of said dampers being subjected to the pressure of the iiuid in an associated passage and the other side thereof being subjected to the pressure at said source of supply, whereby when said differential pressure exceeds a predetermined value said dampers move to closed position, a plurality of automatic means for controlling the operation of said dampers, one of said automatic means being provided for each of said dampers, each of said automatic mean. comprising a piston and a cylinder therefor, oni end of each of said pistons being subjected to the fluid pressure at said source of supply, an auxiliary source of iiuid pressure, means connecting the other end of said pistons to said auxiliary source of pressure, valve means for controlling the pressure delivered to said pistons from said auxiliary source of presure, and an adjutable relief valve for maintaining constant the pressure supplied to said pistons from said last mentioned source of pressure.

9. In a device of the class described, the com.- bination of a series of tuyre blocks adapted to receive iiuid from a source of fluid supply, means including dampers defining passages between said source of uid supply and said tuyre blocks, one side of each of said dampers being subjected to the pressure of the iiuid in its associated passage, and the other side thereof being subjected, at least in part, to the pressure at said source of supply, whereby each of said dampers is subjected to a differential pressure, and means acting on each of said dampers and controlled by the iiuid at said source of supply for controlling the operation of said dampers.

10. In a device of the class described, the combination oi a series of tuyre blocks adapted to receive fluid from a source cf supply, means defining inlet passages to said tuyre blocks, a normally open damper provided in each of said passages for controlling the ow of fluid therein, each of said dampers being so disposed that one side thereof is subjected to the pressure in its passage, While'the other side is subjected'to the pressure at said source of supply, whereby when said differential pressure exceeds .a predetermined value said damper moves to closed position, and means operating in response to the pressure at said source of supply for imposing an additional force upon said dampers.

11. In a device of the class described, the combination of a plurality of tuyre blocks having passages therebetween adapted to receive fluid from a source of supply, a plurality of dampers, one for each of said passages for controlling the iiow of fluid thereto, one side of said dampers being subjected to the pressure Aof the iiuid in said passages and the other side thereof being subjected to the fluid pressure at said source of supply, whereby when the differential pressure acting cn any of said dampers exceeds a predetermined value it will move toward closed position, adjustable weight means for each of said dampers tending to hold the same in open position, automatic means for varying the moments of said weights in accordance with the changes in fluid pressure at said source of supply to counteract the changes in diiferential pressure acting on said dampers caused by the changes in pressure .at said source of supply, said automatic means comprising reciprocable means operatively connected to said weights, and a pressure regulator connected to said reciprocable means and operable in one direction by the fluid pressure at said source of supply, and weight means counteracting the operation of said pressure regulator for actuating said reciprocable means and rst mentioned weights in the reverse direction when the pressure at said source of supply decreases.

12. In a device of the class described, the combination of a plurality of tuyre blocks, having passages therebetween adapted to receive fluid from a source of supply, a plurality of dampers, one for each of said passages for controlling the flow of fluid thereto, one side of said dampers being subjected to the pressure of the fluid in said passages and the other side thereof being subjected to the fluid pressure at said source of supply, whereby when the differential pressure acting on any of said dampers exceeds a predetermined value it will move toward closed position, adjustable Weight means for each of said dampers tending to hold the same in open position, manual means for varying the moments oi said weights in accordance with the changes in fluid pressure at said source of supply to counteract the changes in differential pressure acting on said dampers caused by the changes in pressure at said source of supply, said manual means comprising reciprocable means operatively connected to said weights, and indicator means whereby the extent of movement of said reciprocable members .and weights may be determined.

13. In a device of the class described, the combination of a plurality of tuyre blocks, having passages therebetween adapted to receive uid from a source of supply, a plurality of dampers, one for each of said passages for controlling the flow of fluid thereto, one side of said dampers being subjected to the pressure of the fluid in said passages and the other side thereof being subjected to the fluid pressure at said source of supply, whereby when the differential pressure acting on any of said dampers exceeds a predetermined value it will move toward closed position, adjustable weight means for each of said dampers tending to hold the same in open position, automatic means for varying the moments cru lator 'foractuating said reciprocable means and rst mentioned Weights in the reverse direction when the pressure at said source of supply decreases, means for disconnecting said pressure regulator Vfrom said reciprocable means to permit manual adjustment thereof, and indicator means whereby the extent of movement of said reciprocable means and Weights may be determined.

WILLIAM V. SAUTER.

HOWARD F. LAWRENCE. 

